Frames for use in serigraphic processes



' 1969 E. F. J. PRINZHORN ,55

FRAMES FOR USE IN SERIGHAPHIC PROCESSES Filed Jan. 23, 1967 r I Lin n 32 ii 42 .1 snnnl INVENTOR. [RA/157 E J, PRl/VZHORN A T'TORNE Y5.

United States Patent 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to frames for stretching screen for use in serigraphic processes. A frame according to the present invention comprises a plurality of support members defining a periphery. Clamp means comprising a first and a second clamp member and a securing means therebetween, is attached to at least one of the support members by an adjustment means. The screen intended to be stretched is placed within the periphery defined by the support members, and a margin of it is sandwiched between the securing means and the clamp members. An opposite margin of the screen is secured to an opposite support member, and the adjustment means is operated to provide adjustment of the position of the assembled clamp means, thereby providing adjustment for the tension in the screen.

This invention relates to frames for stretching screen, such as silk, filament and stainless steel screens for use in serigraphic processes and the like.

Serigraphy is basically a process for producing an image on a working surface such as a sheet of paper, with the aid of a stencil. The process is particularly useful for producing a multicolored image. The process involves stretching a screen on a frame and applying a stencil on the screen conforming to the areas not to be colored in the final image. For example, the stencil may be laid onto the screen. The screen is laid adjacent to a working surface, such as paper or bristol board, and the desired color pigment is squeegeed across the screen. The pigment penetrates those areas of the screen not covered by the stencil to produce an image on the working surface. The screen may then be removed from the working surface, and the stencil may be removed from the screen. In multicolor processes, different stencils are sequentially applied on the screen, and the process is repeated with each stencil and respective colors until the multicolored image is complete.

The word serigraphy is often used to refer to the art of silk screening. However, it is to be understood that since the present invention contemplates stretching a wide variety of types of screen, such as silk, filament and stainless steel screens, the terms serigraphy and serigraphic as used herein are intended to be used in their broadest sense, relating to those processes for producing an image with a screen-type stencil, and are not to be limited to processes using only screens made of silk.

Heretofore, frames for stretching screen material such as screens made of silk, have been inadequate because there has been a tendency for the screen to break loose and dislodge from the frame when the screen is stretched in tension by the frame. Furthermore, prior frames for screens tended to warp as tension was increased on the screen, thereby causing a separation between the warped screen and the fiat working surface. Another problem was that the frames were not adjustable, length and widthwise, so as to enable stretching of various sizes of screen.

An object of the present invention is to provide a frame for stretching a screen which holds the screen tightly regardless of the tension imposed upon the screen.

A desirable but optional object of the present invention is to provide a frame from stretching a screen which is substantially free from warpage.

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Another desirable but optional object ofthe present invention is to provide a frame for stretching a screen which may be fitted with varying sizes of length and width sides to accommodate various sizes of screens.

According to the present invention, a frame for stretching a screen for use in a serigraphic process is provided with clamping means which holds the screen with an increasing clamping force as the tension on the screen is increased. Adjustable means is attached to the clamp means whereby the tension on the screen may be adjusted as desired.

The above and other features of this invention will be more fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 is a perspective view, partly in cutaway crosssection of a frame for stretching a screen according to the presently preferred embodiment of the invention;

FIG. 2 is a cutaway bottom elevation of the frame illustrated in FIG. 1;

FIGS. 3 and 4 are cutaway side views taken at lines 3-3 and 44 respectively, in FIG. 2;

FIG. 5 is a perspective view, partly in cutaway crosssection, of a modification of the frame illustrated in FIG. 1;

FIG. 6 is a cutaway side view taken at plane 6-6 in FIG. 5; and

FIG. 7 is a bottom elevation of a frame according to the present invention.

Referring to FIGS. 14 and 7 there is illustrated a frame for stretching a screen having side support members, such as extrusion 10 and corner fittings 12. It is to be understood that a particular frame Will usually have four extrusions 10 and four corner fittings 12 fitted together in a rectangular configuration to define the periphery 13 of the frame. The length of the extrusions 10 may vary in accordance with the length and width of the frame as desired, but it is understood that opposite extrusions will usually have approximately the same length.

Extrusion 10 contains an internal channel 14 into which is fitted slide bar 16 (sometimes called first clamp member). The cross-section of bar 16 generally conforms to the cross-section of internal channel 14, except that the bar is narrower than the channel so as to permit the bar to slide from right to left (as illustrated in FIGS. 3 and 4). Recess 18 is formed through the length of bar 16 and bar 20 (sometime called third clamp member) is fitted in the space between channel 14 and recess 18. Bar 20 has a width less than that of recess 18 so it may independently slide from the right to the left (as illustrated in FIGS. *3 and 4).

Recess 22 is formed in bar 16 opposite from recess 18 and has a semi-circular face 24. Bar 26, (sometimes called second clamp member) which has a semi-circular face 28, is placed in recess 22 and has a width less than the width of recess 22 so that the bar 26 is free to slide independently from right to left (as illustrated in FIGS. 3 and 4).

A plurality of fastening means such as bolts 30 are provided having their heads countersunk into bar 26 and extending through passages 32 in bar 1=6. Bolts 30 are threaded into suitable threaded portions of bar 20. Dowel 34 (sometimes called securing means) is placed between semi-circular faces 24 and 28 on bars 16 and 26, respectively, and a screen 36 such as a stainless steel, filament or silk screen, is placed over face 38 of extrusion 10, through opening 40 and around dowel 34 between faces 24 and 28, respectively.

The screen may be inserted by loosening bolts 30 and sliding bars 20 and 26 to the left (as shown in the drawings). A margin of the screen may then be laid in position over bar 16 and dowel 34 is placed over the screen to sandwich the screen between face 24 and dowel 34. Bars 3 and 26 and bolt are slid back to the right against the dowel so as to tightly sandwich screen 36 between face 28 and dowel 34. Bolt 30 is then tightened to clamp bar 16 between bars 20 and 26, thereby assembling the bars and securing the screen between dowel 34 and faces 24 and 28.

A plurality of bolts 42 (sometimes called adjustment means) are supported by extrusion 10 and threaded into bar 16. Bolts 42 are tightened causing the axial pull of the threads of bolt 42 to move bar 16 to the left (as shown in the drawings), thereby moving bars 20 and 26, dowel 34 and opening to the left, and thereby increasing tension on screen 36.

As tension is increased on screen 36, the dowel tends to impart more resistive force on the screen adjacent opening 40, thereby increasing the clamping force between dowel 34 and faces 24 and 28. Therefore, as the tension increases on screen 36, the clamping force provided by the dowel on the screen becomes greater. It is preferable that dowel 34 be constructed of wood so as to provide a soft clamping surface between the screen and the dowel. Furthermore, the wood of the dowel expands when wetted thereby providing an even tighter fit between the dowel faces 24 and 28. Extrusion 10 and bars 16, 20 and 26 may be constructed from suitable durable metal, such as steel or aluminum.

Extrusions 10 are provided with suitable openings 44 and 46 adapted to mate with protrusions 48 and 50, respectively, on corner fitting 12. Bars 16, 20 and 216 are slid into extrusion 10 from one end and positioned in place by protruding face 52 of corner fitting 12 which fits a short distance into the end of channel 14 of extrusion 10.

Extrusions 10 preferably include protrusions 54 having faces 56 and 58 formed approximately to the length of the extrusion. When the extrusion is mated to a corner fitting, protrusion 54 mates with a like protrusion from another extrusion 10 to form corner 60 of the frame (FIG. 2). Excessive screen material adjacent the corner may be tucked beneath protrusions 54 into slot 62 formed between faces 58 and corner fiting 12.

FIGS. 5 and 6 illustrate a modification of the frame illustrated in FIGS. 1-4. Support members, such as extrusion 70, form the periphery of the frame and are provided with openings 72 for mating with protrusions 74 of corner fittings 76. A floating frame 78 is provided having clamp members 80 and 82, comprising bars 84 and 86 encased by casings 88 and 90, respectively. Bars 84 and 86 are preferably constructed from Wood, while casings 88 and 90 are formed from durable metal, such as steel or aluminum. Semi-circular faces 90 and 82 are formed in each of bars 84 and 86 and support dowel 96, (sometimes called securing means), which is conveniently constructed from wood.

A margin of the screen (not shown) to be stretched is placed in opening 98 and around dowel 96 so as to be sandwiched between dowel 96 and faces 92 and 94, respectively. Bolt 100 (sometimes called adjustment means) extend through frame 78 and extrusion 70. Nut 102 (sometimes called clamping means) on the threaded portion of bolt 100 is tightened to fasten pieces 80 and 82 together, thereby clamping the screen between bars 84 and 86 and dowel 96. Bolt 100 is turned, causing an axial pull on the assembled floating frame 78, thereby in creasing the tension on the screen.

The length of extrusions 10 in the embodiment illustrated in FIGS. 1-4, and of extrusions 70 in the embodiment illustrated in FIGS, 5 and 6 may be any desirable length. A user may desire to keep several extrusions of various lengths on hand to facilitate the stretching of screens of various sizes. Thus, a user need only keep four corner fittings on hand and may fashion a frame suitable to the size of the screen with which he is working. The frame is easily taken apart to facilitate storage in confined areas. The frame is easily assembled by slide-fitting protrusions 48 and into openings 44 and 46, in the embodiment illustrated in FIGS. I4; and by slide-fitting protrusions 74 into opening 72 in the embodiment illustrated in FIGS. 5 and 6. The protrusions may be press-fitted into the respective openings, or suitable clamping means, such as a lock bolt (not shown) may be provided to lock the extrusions to the corner fittings.

In the use of the frame illustrated in FIGS. 1-4 in a serigraphic process, extrusions 10 are assembled to corner fittings 12, and screen 36 is clamped to extrusions 10 in the manner hereinbefore described. The frame is then turned upside down from the position illustrated in FIGS. 1-4 so that screen 36 is contiguous to a suitable working surface (not shown), such as a sheet of paper. Bolts 42 are then turned to thereby stretch screen 36. The screen is then ready for use in a serigraphic process in a manner well known to the art. Since the tension forces in the screen are transferred to bar 16, which in turn is supported in channel 14, the tension forces are transmitted axially to bolts 42, thereby preventing warping of the bolts and the frame.

In the use of the frame illustrated in FIGS. 5 and 6, extrusions 70 are attached to corner fitting 76 and floating frame 78 is attached to extrusion 70. The screen (not shown) is assembled to the floating frame in the manner hereinbefore described, and the frame is turned upside down from the position illustrated in FIGS. 5 and 6 and laid contiguous to a suitable working surface (not shown) such as a sheet of paper. The screen is then made ready for use in a serigraphic process by tightening bolts to stretch the screen. Since bolts 100 preferably are located closed to dowel 96, tension forces in the screen are transmitted to the dowel, and transferred substantially axially to bolts 1110 thereby substantially preventing warping of the bolts and frames.

With a frame according to the present invention, there is little likelihood that the frame will warp due to tension of the screen. This is due partly to the fact that the frame is preferably constructed from, or encased in, metal, and partly because tension forces of the screen are transferred axially to the adjustment bolts.

The present invention thus provides a frame for stretching a screen, such as a silk screen and the like, having a positive clamp on the screen to prevent the screen from breaking loose and dislodging from the frame. The frame is easily constructed and substantially free from warping. The extrusions may be provided in various lengths so that a user will not be confined to a single-sized frame, but instead may assemble a frame having a size in accordance with his own particular needs, still using the standard and same corner fittings. Conversely, the manufacturer need only stock a group of identical corner fittings and a number of indeterminate extrusions for forming frames of various sizes.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.

I claim:

1. Clamp means for use with a frame for stretching a screen for use in a serigraphic process, said frame including a plurality of support members defining the periphery of the frame, adjustment means mounted to at least one of the support members for supporting said clamp means, said clamp means comprising: first and second clamp members each having a substantially semi-circular face; said first and second clamp members defining an opening between them; and securing means comprising a dowel positioned between said clamp members and adapted to secure a screen to said clamp members, whereby one margin of a screen to be stretched may be passed through said opening and around said dowel thereby sandwiching said screen between said dowel and the semicircular face on each of said first and second clamp members, and a margin of said screen opposite said one margin may be secured to a support member opposite said one support member, said adjustment means being operable to move the assembled clamp members relative to said one support member thereby to adjust tension in said screen.

2. Clamp means according to claim 1 wherein each of said first clamp members includes a recess and a respective second clamp member is slidably supported within said recess; a plurality of third clamp members and a plurality of fastening means, each of said fastening means being supported by a respective one of said second clamp members and passing through a respective one of said first clamp members and attached to a respective one of said third clamp members, each fastening means being adapted to clamp a respective first clamp member between a respective second clamp member and a respective third clamp member.

3. Support means for use with a frame for stretching a screen for use in a serigraphic process, said frame including adjustment means mounted to the support means, and clamp means connected to the adjustment means and adapted to supported a margin of the screen intended to be stretched, said support means comprising: a plurality of extrusions each having a channel, said clamp means being supported within each channel; a plurality of corner fitting means; and mutually mateable means on each of said fittings and extrusions for attaching two of said extrusions to each of said fitting means, thereby forming adjacent sides of said frame.

4. A frame for stretching a screen for use in a seri graphic process, said frame comprising: a plurality of support members defining the periphery of the frame, each of the support members being adapted to support a margin of a screen intended to be stretched; first and second clamp members each having a semi-circular face; said first and second clam-p members defining an opening between them; securing means comprising a dowel positioned between said clamp members and adapted to secure a screen to said clamp members; and adjustment means mounted to at least one of said support members and connected to the clamp members for adjusting the relative position of the assembled clamp members, whereby one margin of a screen to be stretched may be passed through said opening and around said dowel thereby sandwiching said screen between said dowel and the semi-circular face of each of said first and second clamp members, and a margin of said screen opposite from said one margin may be secured to a support member opposite said one support member, and adjustment means being operable to move said assembled clamp members relative to said one support member to thereby adjust the tension in said screen.

5. A frame for stretching a screen for use in a serigraphic process, said frame comprising: a plurality of support members defining the periphery of the frame, each of said support members comprising an extrusion, each extrusion being adapted to support a margin of a screen intended to be stretched; a plurality of fitting means; attachment means for attaching two of said extrusions to each of said fitting means to thereby form adjacent sides of same frame; a channel within each of said extrusion; first and second clamp members supported within each channel; said first and second clamp members defining an opening between them; securing means positioned between said clamp members and adapted to secure a screen to said clamp members and adjustment means mounted to at least one of said support members and connected to the clamp members for adjusting the relative position of the assembled clamp members, whereby one margin of a screen to be stretched may be sandwiched between said first clamp member and said securing means and between said second clamp member and said securing means, and a margin of said screen opposite from said one margin may be secured to a support member opposite said one support member, said adjustment means being operable to move said assembled clamp members relative to one support member thereby to adjust the tension in said screen.

6. A farme according to claim 5 wherein said attach ment means comprises mutually matea'ble means on each of said fittings and extrusions whereby the extrusions mate with the fittings.

7. A frame according to claim 5 wherein each of said first and second clamp members includes a substantially semi-circular face, and said securing means comprises a dowel, whereby the screen may be passed through said opening and around said dowel thereby sandwiching said screen between said dowel and the semi-circular face on each of said first and second clamp members.

8. 'A frame according to clam 7 wherein each of said first clamp members includes a recess and a respective second clamp member slidably supported within said recess; a plurality of third clamp members and a plurality of fastening means, each of said fastening means being supported by a respective one of said second clamp membres and passing through a respective one of said first clamp members and attached to a respective one of said third clamp members, each fastening means being adapted to clamp a respective first clamp member between a respective second clamp member and a respective third clamp member.

9. A frame according to claim 5 wherein said first and second clamp members form a floating frame.

10. A frame according to claim 9 wherein each of said first and second clamp members includes a substantially semi-circular face, and said securing means comprises a dowel, whereby the screen may be passed through said opening and around said dowel thereby sandwiching said screen between said dowel and the semi-circular face on each of said first and second clamp members.

11. A frame according to claim 10 wherein said adjustment means comprises a plurality of threaded fasteners each having an axis, said threaded fasteners being fastened to a respective second clamp member and passed through a respective first clamp member and supported by a respective etrusion; and engagement means on a threaded portion of said threaded fasteners, whereby the clamp members may be clamped together by axially rotating the engagement means on said threaded fasteners, thereby causing an axial pull to clamp the clamp members together, and the position of the assembled clamp members relative to the extrusions may be adjusted by axially rotating said threaded fasteners thereby causing an axial pull between the extrusions and the respective assembled clamp members.

References Cited UNITED STATES PATENTS 1,118,858 11/1914 Hiegel 38102.91 X 1,335,806 3/1920 Trueb 38102.91 2,325,268 7/ 1943 Nelson 381 02.1 2,630,652 3/ 1953 Amado 38-10291 2,893,162 7/ 1959 Knowles 38--102.1

FOREIGN PATENTS 519,040 4/1953 Belgium. 353,853 5/1905 France.

PATRICK D. LAWSON, Primary Examiner.

US. Cl. X. R. 101115 

